opencascade: new variants

[wdconinc]

OpenCascade has several major modules and not every application needs all of them. This adds variants for the various modules.

It also updates the 3rdparty dependency treatment.

[wdconinc]

@spackbot fix style

[spackbot-app]

Let me see if I can fix that for you!

[spackbot-app]

I was able to run spack style --fix for you!

spack style --fix

==> Running style checks on spack
  selected: isort, black, flake8, mypy
==> Modified files
  var/spack/repos/builtin/packages/opencascade/package.py
==> Running isort checks
  isort checks were clean
==> Running black checks
reformatted var/spack/repos/builtin/packages/opencascade/package.py
All done! ✨ 🍰 ✨
1 file reformatted.
  black checks were clean
==> Running flake8 checks
  flake8 checks were clean
==> Running mypy checks
Success: no issues found in 576 source files
  mypy checks were clean
==> spack style checks were clean

Keep in mind that I cannot fix your flake8 or mypy errors, so if you have any you'll need to fix them and update the pull request. If I was able to push to your branch, if you make further changes you will need to pull from your updated branch before pushing again.

I've updated the branch with style fixes.

[wdconinc]

@spackbot fix style

[spackbot-app]

Let me see if I can fix that for you!

[spackbot-app]

I was able to run spack style --fix for you!

spack style --fix

==> Running style checks on spack
  selected: isort, black, flake8, mypy
==> Modified files
  var/spack/repos/builtin/packages/opencascade/package.py
==> Running isort checks
  isort checks were clean
==> Running black checks
reformatted var/spack/repos/builtin/packages/opencascade/package.py
All done! ✨ 🍰 ✨
1 file reformatted.
  black checks were clean
==> Running flake8 checks
  flake8 checks were clean
==> Running mypy checks
Success: no issues found in 578 source files
  mypy checks were clean
==> spack style checks were clean

Keep in mind that I cannot fix your flake8 or mypy errors, so if you have any you'll need to fix them and update the pull request. If I was able to push to your branch, if you make further changes you will need to pull from your updated branch before pushing again.

I've updated the branch with style fixes.

[wdconinc]

FYI, the splitting into different modules is a first step towards making some of the dependencies dependent on the enabled modules. E.g. +vtk doesn't make sense unless +visualization, but +tbb does make sense for the foundation classes. I can either do all that work in this PR or in a different one. LMK.

[alecbcs]

Looks good to me. Thank you for the contribution @wdconinc! Would you like to continue work on this PR to segment out the dependencies or add it in a follow up?

[wdconinc]

I just compared my notes and there was one issue in this PR that I just fixed, but the rest is for a future PR (i.e. adding conditionals to the e.g. gl variants and dependencies). This is ready for merging.

[alecbcs]

Looks good to me!